CN113583253B - Efficient synthesis method for carboxylation of intrinsic microporous polymer - Google Patents

Abstract

The invention relates to a high-efficiency synthesis method for carboxylation of an inherent microporous polymer. The method comprises the following steps: the inherent microporous polymer is mixed with water, glacial acetic acid and concentrated sulfuric acid and then put into a hydrothermal reaction kettle for hydrothermal reaction. The temperature of the hydrothermal reaction is 150-170 ℃, and the time of the hydrothermal reaction is 5-7 hours. Hydrolysis is carried out under the acidic condition of glacial acetic acid and concentrated sulfuric acid, and the hydrolysis conversion rate of PIM-1 is improved under the combined action of pressure and temperature in a hydrothermal reaction kettle. Has better hydrolysis conversion rate compared with the alkaline hydrolysis method.

Description

Efficient synthesis method for carboxylation of intrinsic microporous polymer

Technical Field

The invention belongs to the technical field of gas separation membranes, and particularly relates to a high-efficiency synthesis method for carboxylation of an inherent microporous polymer.

Background

The disclosure of this background section is only intended to increase the understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art already known to those of ordinary skill in the art.

Carbon capture, utilization and storage refers to capturing carbon dioxide emissions (CCUS) and using it in a range of industrial applications or related technologies stored underground. By 2020, the global carbon dioxide capture capacity has reached 4000 ten thousand tons. However, to achieve the goal of the "Paris agreement," global carbon capture capability may be required to reach 10 billion tons per year. As a default technology for the current-stage CCUS, the liquid-phase absorption column can be injected on a scale of up to about millions of tons/year. However, the liquid phase absorber requires a great capital investment and both efficiency and energy consumption problems remain to be solved. Membrane separation technology would be an effective means of gas separation. Compared with the existing chemical and thermal separation processes, such as low-temperature distillation, pressure swing adsorption, cryogenic separation, amine absorption and the like, the separation membrane technology has the advantages of low investment, energy conservation, simple operation, light weight, small occupied area, no phase change and the like. Gas separation membranes have found industrial application in the separation and recovery of hydrogen, air separation, acid gas separation, dehumidification, and recovery of organic vapors.

The key to future gas separation membrane-based carbon capture and storage solutions is the significant reduction in total membrane area required, yet the need to maintain high selectivity, high permeability. Budd and Mckeown first proposed PIM-1 synthesis in 2004, which is a subclass of microporous polymers, have rigid, twisted backbone structures, which have high thermal stability, high specific surface area, high mechanical strength, good processability, adjustable chemical function, and good gas transport properties, and have been widely used. In particular, PIM-1 breaks through the gas permeability limit of conventional polymer membranes (Robeson upper limit 1991) in terms of gas transport properties, based on a dissolution permeation model. The permeability of PIM-1 membrane to carbon dioxide reaches approximately 4000 barrers, butSelectivity is relatively low, e.g. CO ₂ /N ₂ 14.6 CO ₂ /CH ₄ 11. Because of relatively low gas selectivity of PIM-1 membrane and physical aging and plasticizing phenomena, the treatment of functional modification, crosslinking modification, preparation of mixed matrix membrane and the like of PIM-1 are performed at present.

In view of the presence of cyano functionality in PIM-1, studies have been made on the conversion of cyano groups to carboxyl groups, and in general, the hydrolysis of cyano groups can be carried out by heating under acidic or basic conditions. In the alkaline hydrolysis process, hydroxyl ions are taken as strong alkali to attack cyano carbon to generate anions, then protons are extracted, amide groups are generated through rearrangement, and the amide is hydrolyzed to obtain carboxylic acid. However, for high molecular weight polymers with cyano groups, the hydrolysis process is slow and inefficient, mainly because of NH ₂ ^- Is a stronger base and less favored leaving group, and the tetrahedral intermediate formed can revert to the amide starting material or form the carboxylic acid product. The former has also made extensive studies on basic hydrolysis of the cyano group of PIM-1, and Naiying Du first performed carboxylation treatment on PIM-1, but ignored the intermediate product of cyano hydrolysis. Through the study of Bekir Satilmis et al, it was further determined that amide, carboxylate, ammonium carboxylate and sodium carboxylate were present in the hydrolysis product and that the final conversion was only 51%. The 5 hour alkaline hydrolysis product was further demonstrated to be essentially amide functionalized PIM-1 by BagusSantoso et al, which characterized three model compounds. Jun Woo Jeon et al obtained carboxylated PIM-1 with 92% conversion by extending the alkaline hydrolysis time to 360 hours, and the test results showed that carboxylated PIM-1 had excellent performance and showed higher selectivity than PIM, such as CO ₂ /N ₂ Selectivity is 53.6, CO ₂ /CH ₄ 25.2, etc. However, extremely slow reaction efficiency severely affects mass production.

On the other hand, under acidic hydrolysis conditions, cyano groups are protonated under acidic conditions, cyano carbon atoms are easily subjected to nucleophilic addition reaction with water, then protons are eliminated, amide is formed through enol rearrangement, and the amide is hydrolyzed to obtain carboxylic acid. Acid hydrolysis by retention of protonated intermediates andreleasing a more stable leaving group NH ₂ ^- Provides an effective driving force for nucleophilic attack and may be a better choice for hydrolysis of PIM-1 cyano. The use of Wei-Hsuan Wu et al was limited by the fact that PIM-COOH was obtained at a conversion of about 83% by acidic hydrolysis with the addition of nitrous acid. Katherine Mizrahi Rodriguez et al developed an optimized acid hydrolysis method using PIM-1 post polymerization to give conversion at 48h>89% PIM-COOH. Has high carbon dioxide selectivity and film forming property, but the reaction time is longer, which affects the preparation rate.

Disclosure of Invention

In view of the above problems in the prior art, it is an object of the present invention to provide a highly efficient synthesis method for carboxylation of inherently microporous polymers. Solves the problems of complex reaction process, low conversion rate and long reaction time in the hydrolysis process of PIM-1.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a high efficiency synthetic method for carboxylation of inherently microporous polymers, said method comprising:

the inherent microporous polymer (PIM-1) is mixed with water, glacial acetic acid and concentrated sulfuric acid and then put into a hydrothermal reaction kettle for hydrothermal reaction.

The inherent microporous polymer (PIM-1) reacts under the acidic condition, cyano groups of the PIM-1 are protonated, cyano carbon atoms are easy to carry out nucleophilic addition reaction with water, then protons are eliminated, amide is generated through enol rearrangement, and the amide is hydrolyzed to obtain carboxylic acid. Acid hydrolysis by retention of protonated intermediate and release of the more stable leaving group NH ₂ ^- Provides an effective driving force for nucleophilic attack. The reaction in the hydrothermal reaction kettle can accelerate the speed and the capturing capability of hydrogen ions obtained in the hydrolysis process of PIM-1, and can make the inherently microporous polymer quickly carry out carboxylation reaction.

In some embodiments of the invention, the temperature of the hydrothermal reaction is 150-170 ℃ and the time of the hydrothermal reaction is 5-7 hours; further, the temperature of the hydrothermal reaction was 160℃and the time of the hydrothermal reaction was 6 hours. Carboxylation of PIM-1 is difficult and the driving force for the reaction is small, so cyano hydrolysis currently takes a long time to complete 85% conversion, and can provide a large driving force at the temperature of the hydrothermal reaction described above.

In some embodiments of the invention, the ratio of PIM-1 to water, glacial acetic acid, concentrated sulfuric acid is 0.4-0.6g:28-32ml:8-12ml:28-32ml; preferably 0.5g:30ml:10ml:30ml. The acidic condition is provided by the concentrated sulfuric acid and the glacial acetic acid, the concentration of the concentrated sulfuric acid is higher, the main effect is exerted, the acidity of the glacial acetic acid is weaker, the concentrated sulfuric acid can be diluted to a certain extent, and meanwhile, the effect of providing protons is achieved. Under the hydrothermal condition, the concentrated sulfuric acid and glacial acetic acid are matched to form a mild acidic condition, which is favorable for the protonation reaction.

In some embodiments of the invention, the mass percent of concentrated sulfuric acid is 70% or more. The concentrated sulfuric acid has the concentration with larger mass percent and plays a role of strong acid.

In some embodiments of the invention, the product obtained after the hydrothermal reaction is neutralised and filtered with water. The reaction was stopped and the acidity was diluted.

In some embodiments of the invention, the solid obtained after filtration is refluxed in an acidic aqueous solution and then filtered to obtain the carboxylated inherently microporous polymer (PIM-COOH). The residual acidic medium on the solid surface is removed by a reflux process.

In some embodiments of the invention, the acidic aqueous solution is a dilute sulfuric acid aqueous solution having a concentration of 0.2-0.4%; further 0.3%.

In some embodiments of the invention, PIM-1 is milled prior to the hydrothermal reaction.

In some embodiments of the invention, the total volume of each component in the hydrothermal reaction kettle accounts for 6/10 to 8/10 of the kettle volume; preferably 6.5/10-7.5/10. The reaction kettle is a sealed environment, a certain pressure and a certain temperature are provided for the reaction, the proportion of the mixed components has a larger influence on the reaction of the mixed solution, and the pressure and the temperature provide driving force for the reaction medium, so that the reaction kettle occupies a certain kettle volume, and the conversion rate can be better improved in the actual use process.

One or more of the technical schemes of the invention has the following beneficial effects:

the invention provides a method for improving the hydrolysis and carboxylation conversion rate of PIM-1, which can lead PIM-1 to reach larger conversion rate in a short time, and can realize 92-93% conversion rate in about 6 hours;

hydrolysis is carried out under the acidic condition of glacial acetic acid and concentrated sulfuric acid, and the hydrolysis conversion rate of PIM-1 is improved under the combined action of pressure and temperature in a hydrothermal reaction kettle. Has better hydrolysis conversion rate compared with the alkaline hydrolysis method.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.

FIG. 1 is an infrared spectrum of the products obtained in comparative example 1 and comparative example 2, experiment one showing comparative example 1 and experiment two showing comparative example 2;

FIG. 2 is an infrared spectrum of the product of example 1 and PIM-1;

FIG. 3 is a diagram showing the chemical formulas of PIM-1 and the hydrolysis products of PIM-1 and the principle of cyano acid hydrolysis;

FIG. 4 is a graph showing the hydrolysis conversion of PIM-1 as a function of reaction time.

Detailed Description

It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.

Low temperature synthesis of PIM-1: method for synthesizing PIM at low temperature we performed synthesis based on previous research methods. All glassware was dried overnight in an oven at 130 ℃ to remove residual water prior to use. TTSBI (6.8 g, 20 mmol), TFTPN (4 g, 20 mmol) and anhydrous DMF (100 ml) were added to a 250 ml reaction flask under an argon atmosphere and stirred well at 500 rpm until the monomer dissolved. Next, add anhydrous K to the solution ₂ CO ₃ (5.53 g, 40 mmol) and additional DMF (33 ml). The reaction flask was immediately immersed in a preheated oil bath at 55 ℃ and stirred under an argon atmosphere for 72 hours. After cooling, the reaction solution was slowly poured into a beaker containing 800 ml of 90 ℃ deionized water and stirred for 4 hours to ensure removal of residual salts. The mixture was then filtered and the resulting yellow polymer was dried in a vacuum oven at 130 ℃ for 2 hours. After removal, dissolved in 150 ml of chloroform and precipitated in methanol, the process was repeated 2 times to remove low molecular weight oligomers. After drying in a vacuum oven at 130℃it was dissolved in 200 ml THF and precipitated in a 1:2 mixture of THF and acetone. The polymer was then recovered by vacuum filtration and dried under vacuum at 130 ℃ overnight. TTSBI and TFTPN were purified prior to use, TTSBI was prepared by dissolving in methanol at 60 ℃ and then reprecipitating overnight in dichloromethane. TFTPN was purified by dissolution in hot methanol and slow cooling to recrystallisation overnight. After filtration, the two monomers were dried in a vacuum oven overnight. TFTPN was dried at 35 ℃ and TTSBI was dried at 130 ℃.

The invention will be further illustrated by the following examples

Example 1

Before use, PIM-1 was ground in a mortar at a rate of about 3 s/turn for 3 minutes to make PIM-1 powder finer and to increase the reaction efficiency. 0.5g PIM-1, 30ml deionized water, 10ml glacial acetic acid and 30ml concentrated sulfuric acid were added sequentially to a 100 ml hydrothermal reaction kettle, and the solid powder in the reaction kettle was thoroughly stirred with a glass rod. The hydrothermal reaction was reacted in an oven at 160℃for 6 hours. After cooling, the heterogeneous solution was neutralized with 500 ml of deionized water in a beaker and filtered to give a brown powder. To remove residual reagent, the powder was refluxed with 200 ml of deionized water and 3-4 drops of sulfuric acid in a slightly acidic deionized water solution for about 12 hours, filtered, and dried under vacuum at 130 ℃ overnight.

Example 2

Before use, PIM-1 was ground in a mortar at a rate of about 3 s/turn for 3 minutes to make PIM-1 powder finer and to increase the reaction efficiency. 0.5g PIM-1, 30ml deionized water, 10ml glacial acetic acid and 30ml concentrated sulfuric acid were added sequentially to a 100 ml hydrothermal reaction kettle, and the solid powder in the reaction kettle was thoroughly stirred with a glass rod. The hydrothermal reaction was reacted in an oven at 170 ℃ for 6 hours. After cooling, the heterogeneous solution was neutralized with 500 ml of deionized water in a beaker and filtered to give a brown powder. To remove residual reagent, the powder was refluxed with 200 ml of deionized water and 3-4 drops of sulfuric acid in a slightly acidic deionized water solution for about 12 hours, filtered, and dried under vacuum at 130 ℃ overnight.

Comparative example 1

0.5g PIM-1 was taken in a 50 ml round bottom flask, dissolved in THF and placed on a magnetic stirrer, heated to 80℃and run at 1000r/min. 10ml of NaOH solution with a concentration of 4mol/l and 1 ml of methanol were taken, mixed and poured into a round-bottomed flask. Note that PIM-1 should be dissolved before adding other solutions to avoid clumping of PIM-1; meanwhile, because the solution contains NaOH solution, a layer of vaseline is smeared at the contact part of the reflux condenser and the round bottom flask, so that the adhesion is avoided. The reaction time was 2 days, after cooling, 5 ml of ethyl acetate was added to promote precipitation, and after suction filtration, it was rewashed with methanol. Then adding excessive hydrochloric acid solution to acidify the precipitate, and filtering to obtain the precipitate. Finally, the resultant was dried in a vacuum oven at 110℃for 12 hours.

Comparative example 2

In view of the catalytic role of NaI in cyano hydrolysis in compounds, hydrolysis of PIM-1 was attempted using a dual catalyst of NaI and NaOH. 0.3 g PIM-1 was taken in a 50 ml round bottom flask, and 0.485 g NaI was added to prepare a concentration of 20wt% deionized water and absolute ethanol in a ratio of 1:1, and added to the flask. The mixture was placed in an oil bath magnetic stirrer at 150℃at a rotation speed of 500 rpm for 2 days. After the reaction was completed, 300 ml of slightly acidified (ph=4-5) deionized water was added to boil for 2 hours, and after vacuum filtration, the sample was washed with water until the PH was adjusted to neutral, and dried in a vacuum oven at 80 ℃. The dried powder was dissolved in THF, filtered, and precipitated into water. The precipitate was filtered, rinsed with water and dried in a vacuum oven at 80 ℃.

Comparative example 3

Before use, PIM-1 was ground in a mortar at a rate of about 3 s/turn for 3 minutes to make PIM-1 powder finer and to increase the reaction efficiency. 0.5g PIM-1, 20 ml deionized water, 10ml glacial acetic acid and 20 ml concentrated sulfuric acid were added sequentially to a 100 ml hydrothermal reaction kettle, and the solid powder in the reaction kettle was thoroughly stirred with a glass rod. The hydrothermal reaction was reacted in an oven at 160 ℃ for 20 hours. After cooling, the heterogeneous solution was neutralized with 500 ml of deionized water in a beaker and filtered to give a brown powder. To remove residual reagent, the powder was refluxed with 200 ml of deionized water and 3-4 drops of sulfuric acid in a slightly acidic deionized water solution for about 12 hours, filtered, and dried under vacuum at 130 ℃ overnight.

Comparative example 4

Before use, PIM-1 was ground in a mortar at a rate of about 3 s/turn for 3 minutes to make PIM-1 powder finer and to increase the reaction efficiency. 0.5g PIM-1, 25 ml deionized water, 10ml glacial acetic acid, and 20 ml concentrated sulfuric acid were added sequentially to a 100 ml hydrothermal reaction kettle, and the solid powder in the reaction kettle was thoroughly stirred with a glass rod. The hydrothermal reaction was reacted in an oven at 160 ℃ for 20 hours. After cooling, the heterogeneous solution was neutralized with 500 ml of deionized water in a beaker and filtered to give a brown powder. To remove residual reagent, the powder was refluxed with 200 ml of deionized water and 3-4 drops of sulfuric acid in a slightly acidic deionized water solution for about 12 hours, filtered, and dried under vacuum at 130 ℃ overnight.

Comparative example 5

Before use, PIM-1 was ground in a mortar at a rate of about 3 s/turn for 3 minutes to make PIM-1 powder finer and to increase the reaction efficiency. 0.5g PIM-1, 40 ml deionized water, 10ml glacial acetic acid and 40 ml concentrated sulfuric acid were added sequentially to a 100 ml hydrothermal reaction kettle, and the solid powder in the reaction kettle was thoroughly stirred with a glass rod. The hydrothermal reaction was reacted in an oven at 160 ℃ for 20 hours. After cooling, the heterogeneous solution was neutralized with 500 ml of deionized water in a beaker and filtered to give a brown powder. To remove residual reagent, the powder was refluxed with 200 ml of deionized water and 3-4 drops of sulfuric acid in a slightly acidic deionized water solution for about 12 hours, filtered, and dried under vacuum at 130 ℃ overnight.

As shown in FIG. 1, it was found that, in comparative example 1, 2239cm was found for the spectra of comparative example 1 and comparative example 2 ^-1 There is a distinct C-N peak, indicating that cyano groups are left unconverted, whereas comparative example 2 is absent. But two experiments at 1666cm ^-1 And 1605cm ^-1 There is a distinct amide peak in the vicinity, indicating that the cyano group has been converted to an amide group during hydrolysis. It is preferable that in comparative example 2, the thickness is 1715cm ^-1 There is a weak stretching vibration peak of carboxylic acid c=o, indicating that some cyano groups have been successfully converted to carboxyl groups, but the peak is not prominent. Further organic elemental analysis testing was performed on the product of comparative example 2, and the carboxylic acid conversion was calculated to be 64.07% without substantial conversion. Thus, for comparative example 1, the cyano group was partially converted, and the conversion remained only at the amide group; comparative example 2 achieved partial carboxylation, but the conversion was only 64.07%.

In FIG. 2, the infrared spectra of PIM-COOH prepared in example 1 and PIM-1 were compared, and the infrared spectra of PIM-1 and PIM-COOH were compared to find that PIM-COOH was located at 2240cm ^-1 There is no distinct C-N peak, indicating that C-N has achieved conversion. At 2400-3400cm ^-1 Within the range of 2954cm ^-1 PIM-1 aliphatic and aromatic C-H stretching vibration peaks are nearby, 2400-3400cm ^-1 Is the stretching vibration peak of carboxylic acid O-H, 3000-3400cm ^-1 Is the tensile vibration peak of the amide N-H. 2400-3400cm in PIM-COOH could not be expected due to the overlapping of the two peaks ^-1 This broad and diffuse peak served as an indicator of C-N hydrolysis to carboxylic acid. At 1715cm ^-1 PIM-COOH had a distinct peak of C=O carboxylic acid stretching vibration, but at 1666cm ^-1 And 1605cm ^-1 No significant amide peak appeared. Indicating that the cyano group has been substantially converted to a carboxylic acid without remaining on the amide intermediate. From the fourier infrared spectrum, it can be derived that: the cyano group in PIM-1 has achieved conversion of the carboxyl group, but the amount of conversion is not known and requires further detection.

In PIM-1, the material atomic composition is very consistent with theoretical predictions. Suppose that the only nitrogen source for the hydrolysis product of PIM-1 is from amidated PIM-1 (PIM-CONH) ₂ ) The conversion of PIM-1 in example 1 was calculated as the percent of nitrogen atoms remaining in the hydrolysate divided by the converted PIM-CONH ₂ Ratio of theoretical atomic percent of medium nitrogen. Unlike XPS, which mainly tests surface materials and errors in peak-splitting fitting, we obtained the percentages of the elements by elemental analysis. The conversion was plotted over time in figure 4. From FIG. 4, it is clear that the conversion of PIM-1 was gradually increased with time, 92.6% at 6 hours of reaction, and 98.5% at 42 hours of time. Again, the effectiveness of this method for PIM-1 hydrolysis was demonstrated.

Hydrolysis of PIM-1 was carried out by the three methods described above for example 1, comparative example 1 and comparative example 2. However, comparative examples 1 and 2 did not achieve the desired purpose. From comparative examples 1 and 2, we found that PIM-1 was very difficult in hydrolysis process, low conversion and high molecular weight of PIM-1, so we innovatively performed the reaction under high temperature and high pressure instead of heating only under reflux conditions to ensure rapid hydrolysis of PIM-1. The high temperature and high pressure acidic hydrolysis PIM-1 process of comparative example 3 and comparative example 4, compared to previous studies, has reactant ratios of sulfuric acid: water: glacial acetic acid = 2-2.5:2:1 and requires a preliminary hydrolysis, the overall hydrolysis process is greater than 20 hours, but does not provide hydrolysis conversion. Example 1 by reacting and sulfuric acid: water: glacial acetic acid=3: 3:1 are added into a hydrothermal reaction kettle for reaction in one step to realize the high-carboxylation hydrolysis of cyano groups. The reaction result shows that the conversion rate can reach 92.5% after 6 hours of reaction, and the film forming property is maintained.

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (7)

1. An efficient synthesis method for carboxylation of an inherent microporous polymer is characterized by comprising the following steps: the method comprises the following steps:

mixing the inherent microporous polymer PIM-1 with water, glacial acetic acid and concentrated sulfuric acid, and then placing the mixture into a hydrothermal reaction kettle for hydrothermal reaction;

the temperature of the hydrothermal reaction is 160 ℃, and the time of the hydrothermal reaction is 6 hours;

the total volume of each component in the hydrothermal reaction kettle accounts for 6/10-8/10 of the volume of the kettle;

the proportion of PIM-1 to water, glacial acetic acid and concentrated sulfuric acid is 0.4-0.6g:28-32ml:8-12ml:28-32ml;

the mass percentage of the concentrated sulfuric acid is more than or equal to 70 percent.

2. The efficient synthetic method for carboxylation of inherently microporous polymers according to claim 1, characterized in that: PIM-1 was mixed with water, glacial acetic acid, and concentrated sulfuric acid at a ratio of 0.5 g/30 ml/10 ml/30 ml.

3. The efficient synthetic method for carboxylation of inherently microporous polymers according to claim 1, characterized in that: the product obtained after the hydrothermal reaction is neutralized and filtered by water.

4. A high efficiency synthetic method for carboxylation of inherently microporous polymers according to claim 3, wherein: the solid obtained after filtration is refluxed in an acidic aqueous solution, and then filtered to obtain the carboxylated intrinsic microporous polymer.

5. The efficient synthetic method for carboxylation of inherently microporous polymers according to claim 4, characterized by: the acidic aqueous solution is dilute sulfuric acid aqueous solution, and the concentration of the dilute sulfuric acid aqueous solution is 0.2-0.4%.

6. The efficient synthetic method for carboxylation of inherently microporous polymers according to claim 1, characterized in that: PIM-1 was milled prior to the hydrothermal reaction.

7. The efficient synthetic method for carboxylation of inherently microporous polymers according to claim 1, characterized in that: the total volume of each component in the hydrothermal reaction kettle accounts for 6.5/10-7.5/10 of the volume of the kettle.

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